Not sure what the word for this particular issue would be, but I'd be interested to know if others here have experienced this and how they've handled it.
To make it short - I had speech therapy when I was younger because I had trouble pronouncing my "ch" and "sh" sounds, but I was never diagnosed with any other speech-related issue. However, I have noticed within the past few years, that I've been asked to repeat myself more often because I apparently don't speak clearly or loud enough. (I also used to get comments about having a really nasal quality to my voice)
Where this gets frustrating is that when I've asked for feedback on why the other person couldn't understand what I'd just said, they are never able to give an answer........and because I hear myself speaking at a "normal" pitch and speed, there's not really a way for me to "correct" the problem. And if I try to slow down my speech and speak clearly, sometimes the other person takes it the wrong way and thinks I'm being rude. (my daughter's gotten annoyed with me over this before)